This invention relates to an assembly for transmitting control signals to and/or from a mobile component of an electromechanical machine such as a crane or bulk material handling equipment.
For supplying power to movable cranes or to the mobile parts of bulk material handling equipment such as dredges or stacker/recliners, electric cables are used which can be wound on and unwound from one or several cable drums. The cable drums are provided with slip rings for facilitating or enabling power transfer from the cables on the drums to electric equipment on the mobile machine. For the cables carrying the control signals additional cable drums are usually employed. Other possibilities, already realized, for carrying control signals to the mobile machines involve inductive transmission and transmission via radio links. Disadvantages of the known types of transmission are, for instance, the voltage drop in electric control lines, the limited transmission rates at serial interfaces and capacitive and inductive interferences. The transmission of control signals to mobile machines has required large expenditures.
For transmitting signals between relatively movable parts, particularly relatively rotatable parts, some transmission assemblies include a light guide which, at the transition from the stationary to the movable part, has a separation or gap which must be bridged by the light signal. Transmission of light signals across the gap from an end of the optical fiber connected to the rotatable machine part to an end of the stationary optical fiber presents difficulties requiring expensive designs for a proper transmission of the light signals.
Lines or cables with integrated optical fibers are known, for instance, from British Pat. No. GB-A-20 35 599.
An object of the present invention is to provide a simple assembly for transmitting without interference electrical control signals to a mobile machine component of an electromechanical device such as a crane or bulk material handling equipment, to which device electrical power is carried by a cable windable about a cable drum.